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Periodontal disease is an inflammatory disease caused by periodontopathogenic bacteria, which eventually leads to bone tissue (alveolar bone) destruction as inflammation persists. Periodontal tissues have an immune system against the invasion of these bacteria, however, due to the persistent infection by periodontopathogenic bacteria, the host innate and acquired immunity is impaired, and tissue destruction, including bone tissue destruction, occurs. Osteoclasts are essential for bone destruction. Osteoclast progenitor cells derived from hematopoietic stem cells differentiate into osteoclasts. In addition, bone loss occurs when bone resorption by osteoclasts exceeds bone formation by osteoblasts. In inflammatory bone disease, inflammatory cytokines act on osteoblasts and receptor activator of nuclear factor-κB ligand (RANKL)-producing cells, resulting in osteoclast differentiation and activation. In addition to this mechanism, pathogenic factors of periodontal bacteria and mechanical stress activate osteoclasts and destruct alveolar bone in periodontitis. In this review, we focused on the mechanism of osteoclast activation in periodontitis and provide an overview based on the latest findings. [ABSTRACT FROM AUTHOR]

Studies suggest that analysis of gingival crevicular fluid (GCF) is useful for evaluating periodontal status. In this study, clinical variables related to tooth mobility, and multiple cytokine levels in proximate GCF, were measured at four time points during initial periodontal treatment: before treatment (baseline), after supragingival scaling, after occlusal adjustment, and after scaling and root planing (SRP); 20 teeth from 13 patients with periodontitis were included. Baseline interleukin (IL)-10 level in GCF was significantly higher around teeth that showed substantial improvement in periodontal epithelial surface area (PESA) after SRP than around teeth without PESA improvement. IL-3 and IL-16 levels in GCF at baseline were significantly higher around teeth with a periodontal inflamed surface area (PISA) of 0 mm2 after SRP than around teeth without PISA improvement. In addition, baseline IL-7, IL-11, and IL-12p40 levels in GCF were significantly lower around teeth with decreased mobility after occlusal adjustment than around teeth without decreased mobility. These results suggest that pre-treatment cytokine levels in GCF are useful in predicting the effects of initial periodontal treatment. [ABSTRACT FROM AUTHOR]

Thermoresponsive polymer-modified microfibers were prepared through electrospinning of poly(4-vinylbenzyl chloride) (PVBC) and subsequent surface-initiated atom transfer radical polymerization for grafting poly( N -isopropylacrylamide) (PIPAAm). Electrospinning conditions were optimized to produce large-diameter (20 μm) PVBC microfibers. The amount of PIPAAm grafted on the microfibers was controlled via the IPAAm monomer concentration. The microfibers exhibited thermally controlled cell separation by selective adhesion of normal human dermal fibroblasts in a mixed cell suspension that also contained human umbilical vein endothelial cells. In addition, adipose-derived stem cells (ADSCs) exhibited thermally modulated cell adhesion and detachment, while adhesion of other ADSC-related cells was low. Thus, ADSCs could be separated from a mixture of adipose tissue-derived cells simply by changing the temperature. Overall, the PIPAAm-modified microfibers are potentially applicable as temperature-modulated cell separation materials. Statement of Significance Thermoresponsive poly( N -isopropylacrylamide) (PIPAAm) polymer-modified poly(4-vinylbenzyl chloride) (PVBC) microfibers were prepared via electrospinning of PVBC, followed by surface-initiated ATRP. They formed effective thermally-modulated cell separation materials with large surface areas. Cells adhered and extended along the modified microfibers; this was not observed on previously reported PIPAAm-modified flat substrates. The cellular adhesion enabled separation of fibroblast cells, as well as that of adipose-derived mesenchymal stem cells, from mixtures of similar cells. Thus, the temperature-controlled thermoresponsive microfibers would be potentially useful as cell separation materials. [ABSTRACT FROM AUTHOR]